Manhattan-sized iceberg beginning to break apart

This iceberg, named PII-2012, is beginning to go to pieces off the coast of northwest Greenland after breaking from the Petermann Glacier in mid-July. (Photo: NASA Earth Observatory)

Off the coast of northwest Greenland, an enormous iceberg is beginning to go to pieces.

The huge ice chunk, named PII-2012, was originally part of the Petermann Glacier, but broke away from the glacier in mid-July in a process called calving.

By the end of July the Manhattan-size chunk of ice had nearly reached the mouth of a fjord that opens on the Nares Strait, a narrow stretch of ocean that separates Greenland from Canada.

Now it's made its way into the strait, and has begun to break into several large pieces that could act as hazards for ships negotiating the narrow water body.

NASA's Terra satellite captured this natural-color image on Sept. 13, which shows the main berg and two smaller fragments. This iceberg calved along a rift on the Petermann Glacier that had been visible in satellite imagery for several years.

The Petermann Glacier and other glaciers wind through Greenland's ice sheet, acting like slow-moving conveyor belts. They move ice from the middle of the frigid island to the sea, where they eventually give birth to enormous icebergs like this one.